U.S. patent application number 13/576163 was filed with the patent office on 2012-11-08 for light source unit, lighting device, display device and television receiver.
This patent application is currently assigned to SHARP KABUSHIKI KAISHA. Invention is credited to Yuya Takano.
Application Number | 20120281155 13/576163 |
Document ID | / |
Family ID | 44482785 |
Filed Date | 2012-11-08 |
United States Patent
Application |
20120281155 |
Kind Code |
A1 |
Takano; Yuya |
November 8, 2012 |
LIGHT SOURCE UNIT, LIGHTING DEVICE, DISPLAY DEVICE AND TELEVISION
RECEIVER
Abstract
A light source unit in which color reproduction range is widened
and uneven brightness and color unevenness are less likely to occur
is provided. The light source unit includes light source sets 21
each of which includes a first light source 22 and a second light
source, and an LED board 27 on which the sets 21 are arranged. The
first source 22 includes a first LED chip 23 configured to emit at
least a color of light of red, green or blue and phosphors excited
by the light to emit light, colors of which are different from the
color of the light from the chip 23. The second source 26 is
configured to emit at least a color of light of cyan, magenta or
yellow. The first source 22A in one of the adjacent sets and the
second source 26B in another one of the adjacent sets are arranged
adjacent to each other in an arrangement direction in which the
adjacent sets are arranged.
Inventors: |
Takano; Yuya; (Osaka-shi,
JP) |
Assignee: |
SHARP KABUSHIKI KAISHA
Osaka-shi, Osaka
JP
|
Family ID: |
44482785 |
Appl. No.: |
13/576163 |
Filed: |
January 24, 2011 |
PCT Filed: |
January 24, 2011 |
PCT NO: |
PCT/JP2011/051175 |
371 Date: |
July 31, 2012 |
Current U.S.
Class: |
348/790 ;
348/E3.011; 349/69; 362/231; 362/612 |
Current CPC
Class: |
H01L 25/0753 20130101;
H01L 2924/0002 20130101; G02F 1/133617 20130101; G02F 1/133603
20130101; H01L 33/50 20130101; G02B 6/0068 20130101; G02F 1/133615
20130101; H01L 2924/0002 20130101; G02F 1/133621 20130101; G02B
6/0073 20130101; H01L 2924/00 20130101; G02B 6/003 20130101 |
Class at
Publication: |
348/790 ;
362/231; 362/612; 349/69; 348/E03.011 |
International
Class: |
F21V 9/08 20060101
F21V009/08; H04N 3/10 20060101 H04N003/10; G02F 1/13357 20060101
G02F001/13357; F21V 5/04 20060101 F21V005/04; F21V 8/00 20060101
F21V008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2010 |
JP |
2010-032750 |
Claims
1. A light source unit comprising: a board; and a plurality of
light source sets arranged on the board and each of which including
a first light source and a second light source, the first light
source including a first LED chip and a phosphor, the first LED
chip being configured to emit at least a single color of light of
red, green or blue, the phosphor being configured to be excited by
the light from the first LED chip to emit light of a color that is
different from the color of the light emitted from the first LED
chip, and the second light source being configured to emit at least
a single color of light of cyan, magenta or yellow, wherein at
least two of the light source sets that are adjacent to each other
are arranged such that the first light source in one of the two
light source sets and the second light source in another one of the
two light source sets are arranged adjacent to each other in an
arrangement direction in which the adjacent light source sets are
arranged.
2. The light source unit according to claim 1, wherein the first
light source and the second light source in each of the light
source sets are arranged on the board in a direction that crosses
the arrangement direction of the light source sets.
3. The light source unit according to claim 1, wherein: the first
light source is configured by sealing the first LED chip with a
resin material; and the phosphor is contained in the resin material
in a dispersed manner.
4. The light source unit according to claim 1, wherein: the first
LED chip is a blue LED chip configured to emit blue light; and the
phosphor includes a red phosphor excited by light from the first
LED chip to emit red light and a green phosphor excited by light
from the first LED chip to emit green light.
5. The light source unit according to claim 4, wherein the red
phosphor is a CASN phosphor.
6. The light source unit according to claim 4, wherein the green
phosphor is a SiAlON-based phosphor.
7. The light source unit according to claim 4, wherein the green
phosphor is a YAG-based phosphor.
8. The light source unit according to claim 1, further comprising a
diffuser lens, wherein: the first light source includes a light
emitting surface; the second light source includes a light emitting
surface; and the diffuser lens is provided so as to cover at least
one of the light emitting surface of the first light source and the
light emitting surface of the second light source and configured to
diffuse light from at least the one of the light emitting surfaces
thereof.
9. A lighting device comprising: the light source unit according to
claim 1; and a housing member housing the light source unit.
10. The lighting device according to claim 9, further comprising a
light guide plate including a light entrance surface and a light
exit surface, the light entrance surface facing the light emitting
surface of the first light source and the light emitting surface of
the second light source, wherein light exited from the light
emitting surfaces of the light sources enters the light entrance
surface and exits from the light exit surface.
11. A display device comprising: the lighting device according to
claim 9; and a display panel configured to provide display using
light from the lighting device.
12. The display device according to claim 11, wherein the display
panel is a liquid crystal panel using liquid crystal.
13. A television receiver comprising the display device according
to claim 11.
Description
TECHNICAL FIELD
[0001] The present invention relates to a light source unit, a
lighting device, a display device and a television receiver.
BACKGROUND ART
[0002] In recent years, a type of an image display device including
a television receiver has been shifted from a conventional CRT
display device to a thin display device using a thin display
element such as a liquid crystal panel and a plasma display. An
image display device disclosed in Patent Document 1 has been known.
The image display device includes a liquid crystal panel that
includes a color filter and a lighting device that is configured to
illuminate the liquid crystal panel with light. The lighting device
includes a unit (light source unit) that is configured with a base
board and a plurality of LEDs arranged on the base board. The
lighting device illuminates the liquid crystal panel with light and
the light transmits through the liquid crystal panel and
subsequently passes through the color filter. The color filter
includes color sections, and only the light having certain
wavelengths corresponding to each of the color sections selectively
passes through the color filter. With such a configuration, various
colors of light can be reproduced according to combinations of
light passing through each of the coloring portions.
[0003] Patent Document 1: Japanese Unexamined Patent Publication
No. 2005-352452
PROBLEM TO BE SOLVED BY THE INVENTION
[0004] To achieve high display quality of the image display device,
high color reproduction is required. In the image display device
disclosed in Patent Document 1, the color filter includes a cyan
color portion in addition to color sections of primary colors
including red, green and blue. In the above configuration, color
variations of the color sections are added to achieve high display
quality of the image display device. It may be also effective to
increase a color reproduction range in the light exited from the
lighting device (light exited from the light source unit) and
improvement can be made in this point.
DISCLOSURE OF THE PRESENT INVENTION
[0005] The present invention was accomplished in view of the above
circumstances. It is an object of the present invention to provide
a light source unit in which wide color reproduction range is
achieved and uneven brightness and color unevenness are less likely
to occur. Another object of the present invention is to provide a
lighting device, a display device and a television receiver having
the light source unit.
Means for Solving the Problem
[0006] To solve the above problem, a light source unit according to
the present invention includes a board and a plurality of light
source sets arranged on the board and each of which including a
first light source and a second light source. The first light
source includes a first LED chip and a phosphor. The first LED chip
is configured to emit at least a single color of light of red,
green or blue and the phosphor is configured to be excited by the
light from the first LED chip to emit light, and colors of the
emitted light are different from the color of the light emitted
from the first LED chip. The second light source is configured to
emit at least a single color of light of cyan, magenta or yellow.
At least two of the light source sets that are adjacent to each
other are arranged such that the first light source in one of the
adjacent light source sets and the second light source in another
one of the adjacent light source sets are arranged adjacent to each
other in an arrangement direction in which the adjacent light
source sets are arranged.
[0007] In the light source unit according to the present invention,
the first light source and the second light source are included in
the light source set. Therefore, wide color reproduction range is
achieved compared to a configuration where only the first light
source is included in the light source set. In such a configuration
of the LED unit including a plurality of light source sets 21 each
of which has the first light source 22 and the second light source
26, if two adjacent light source sets are arranged such that the
first light source of one of the light source sets is are arranged
adjacent to the first light source of another one of the light
source sets in the arrangement direction of the two adjacent light
source sets, the first light sources are arranged locally (locally
in a concentrated manner) on the board. This may cause uneven
brightness or color unevenness. According to the present invention,
the first light source in one of the adjacent light source sets and
the second light source in another one of the adjacent light source
sets are arranged adjacent to each other in an arrangement
direction in which the adjacent light source sets are arranged.
With such a configuration, the first light sources are less likely
to be arranged locally on the board, and thus uneven brightness and
color unevenness are less likely to occur.
[0008] In the light source unit, the first light source and the
second light source in each of the light source sets are arranged
on the board in a direction that crosses the arrangement direction
of the light source sets.
[0009] In the light source unit, the first light source may be
configured by sealing the first LED chip with a resin material, and
the phosphor may be contained in the resin material in a dispersed
manner. The phosphor content is appropriately controlled, and thus
the ratio between light from the first light source and light
emitted by the phosphors excited therefrom varies. Therefore, the
chromaticity of light from the first light source is
controlled.
[0010] In the light source unit, the first LED chip may be a blue
LED chip configured to emit blue light. The phosphor may include a
red phosphor excited by light from the first LED chip to emit red
light and a green phosphor excited by light from the first LED chip
to emit green light. With such a configuration, substantially white
light (including white light and substantially white light with a
blue tinge) can be emitted from the first light source. Moreover,
the chromaticity of light of the second light source is controlled.
Accordingly, the chromaticity of light per the light source set can
be controlled. If the first light source emits white light with a
blue tinge, an LED configured to emit yellow light is used for the
second light source. This allows the light source set to exit light
that is closer to white light.
[0011] In the light source unit, the red phosphor may be a CASN
phosphor. A CASN phosphor that is a nitride phosphor is used as a
red phosphor. With such a configuration, the CASN phosphor is
allowed to emit red light with high efficiency compared to a
configuration of using sulfide phosphors and oxide phosphors.
[0012] In the light source unit, the green phosphor may be a
SiAlON-based phosphor. A SiAlON-based phosphor that is a nitride
phosphor is used as a green phosphor. With such a configuration,
the SiAlON-based phosphor is allowed to emit green light with high
efficiency compared to sulfide phosphors and oxide phosphors. In
addition, light emitted from a SiAlON-based phosphor has color
purity higher than a YAG phosphor, for example. Therefore, the
chromaticity of light can be easily controlled.
[0013] In the light source unit, the green phosphor may be a
YAG-based phosphor.
[0014] The light source unit may further include a diffuser lens.
The first light source may include a light emitting surface and the
second light source may include alight emitting surface. The
diffuser lens may be provided so as to cover at least one of the
light emitting surfaces of the first light source and the second
light source and configured to diffuse light from at least the one
of the light emitting surfaces thereof. Light from the first light
source or the second light source is diffused by the diffuser lens.
This causes arrangement intervals between the light source sets to
be increased (namely, the total number of light source sets is
reduced) and achieves uniform brightness.
[0015] Next, to solve the above problem, a lighting device may
include the light source unit and a housing member housing the
light source unit.
[0016] The lighting device may further include a light guide plate
including a light entrance surface and a light exit surface. The
light entrance surface may face the light emitting surface of the
first light source and the light emitting surface of the second
light source. Light exited from the emitting surfaces of the light
sources may enter the light entrance surface and may exit from the
light exit surface.
[0017] Next, to solve the above problem, a display device according
to the present invention may include the above lighting device and
a display panel configured to provide display using light from the
lighting device.
[0018] The display panel may be a liquid crystal panel. The display
device as a liquid crystal display device has a variety of
applications, such as a television display or a personal-computer
display. Particularly, it is suitable for a large screen
display.
[0019] Next, to solve the above problem, a television receiver
according to the present invention may include the above display
device.
Advantageous Effect of the Invention
[0020] According to the present invention, a light source unit that
achieves wide color reproduction range and in which uneven
brightness and color unevenness are less likely to occur, a
lighting device, a display device and a television receiver
including the light source unit are provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is an exploded perspective view illustrating a
general configuration of a television receiver according to a first
embodiment of the present invention;
[0022] FIG. 2 is an exploded perspective view illustrating a
general configuration of a liquid crystal display device included
in the television receiver in FIG. 1;
[0023] FIG. 3 is a cross-sectional view illustrating a sectional
configuration taken along a short side of the liquid crystal
display device in FIG. 2;
[0024] FIG. 4 is a plan view illustrating a light source unit
included in the liquid crystal display device in FIG. 2;
[0025] FIG. 5 is an exploded perspective view illustrating a
general configuration of a liquid crystal display device according
to a second embodiment of the present invention;
[0026] FIG. 6 is a cross-sectional view illustrating a sectional
configuration taken along a short side of the liquid crystal
display device in FIG. 5;
[0027] FIG. 7 is a plan view illustrating a light source unit
included in the liquid crystal display device in FIG. 5; and
[0028] FIG. 8 is a plan view illustrating a light source unit
according to a third embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0029] A first embodiment according to the present invention will
be described with reference to FIGS. 1 to 4. An X axis, a Y-axis
and a Z-axis are described in a part of the drawings, and a
direction of each axial direction corresponds to a direction
described in each drawing. An upper side in FIG. 3 corresponds to a
front-surface side and a lower side in FIG. 3 corresponds to a
rear-surface side.
[0030] As illustrated in FIG. 1, the television receiver TV of the
present embodiment includes the liquid crystal display device 10,
front and rear cabinets Ca, Cb which house the liquid crystal
display device 10 therebetween, a power source P, a tuner T and a
stand S.
[0031] FIG. 2 illustrates an exploded perspective view of the
liquid crystal display device 10. An upper side in FIG. 2
corresponds to a front-surface side and a lower side in FIG. 2
corresponds to a rear-surface side. An entire shape of the liquid
crystal display device 10 is a landscape rectangular. As
illustrated in FIG. 2, the liquid crystal display device 10
includes a liquid crystal panel 12 as a display panel, and a
backlight unit 34 as an external light source. The liquid crystal
panel 12 and the backlight unit 34 are integrally held by a frame
shaped bezel 14 and the like.
[0032] As illustrated in FIG. 2, the liquid crystal panel 12
included in the liquid crystal display device 10 is formed in a
rectangular plan view shape. A long-side direction of the liquid
crystal panel 12 matches a horizontal direction (an X-axis
direction) and a short-side direction thereof matches a vertical
direction (a Y-axis direction). The liquid crystal panel 12 is
configured such that a pair of transparent glass substrates (highly
capable of light transmission) is bonded together with a
predetermined gap therebetween and liquid crystal is sealed between
the glass substrates. On one of the glass substrates, switching
components (for example, TFTs) connected to source lines and gate
lines which are perpendicular to each other, pixel electrodes
connected to the switching components, and an alignment film and
the like are provided. On the other substrate, color filters having
color sections such as R (red), G (green) and B (blue) color
sections arranged in a predetermined pattern, counter electrodes,
and an alignment film and the like are provided. A drive circuit
board (not shown) supplies image data and various control signals
that are necessary to display images to the source lines, the gate
lines and the counter electrodes. Polarizing plates (not shown) are
attached to outer surfaces of the substrates.
[0033] The backlight unit 34 will be described. As illustrated in
FIG. 2, the backlight unit 34 includes a housing member 15
including a backlight chassis 32 and a front chassis 16. The
housing member 15 houses an LED unit 20, a light guide plate 50,
and an optical member 40 therein. The backlight unit 34 according
to the present embodiment is an edge-light-type (side-light-type)
backlight unit in which the light guide plate 50 is arranged right
behind the liquid crystal panel 12 and an LED unit 20 including a
light source set 21 (described later) is arranged on a side end
portion of the light guide plate 50 (a side end portion of the
housing member 15).
[0034] The substantially box-shaped backlight chassis 32 has an
opening on the front-surface side (on the light exit side and the
liquid crystal panel 12 side). The optical member 40 is arranged so
as to cover the opening of the backlight chassis 32. The front
chassis 16 has a rectangular frame shape having an opening 16a
through which the optical member 40 is exposed to the front side.
The front chassis 16 is provided so as to enclose the optical
member 40. As illustrated in FIG. 3, on an inner peripheral end
portion of the front chassis 16, a stepped portion 17 is provided.
A peripheral edge portion of the liquid crystal panel 12 is placed
on the stepped portion 17. With this configuration, the light
exiting from the light guide plate 50 passes through the optical
member 40, and then is applied to a rear surface of the liquid
crystal panel 12 through the opening 16a.
[0035] The backlight chassis 32 is made of metal such as aluminum
material, for example. The backlight chassis 32 includes the bottom
plate 32a and the side plates 32b and 32c each of which rises
shallowly from an outer edge of the corresponding side of the
bottom plate 32a toward the front surface side. The bottom plate
32a is formed in a rectangular plan view shape. A long-side
direction of the bottom plate 32a matches a horizontal direction
(an X-axis direction) and a short-side direction thereof matches a
vertical direction (a Y-axis direction). A power supply circuit
board (not shown) configured to supply power to the LED unit 20 is
mounted on the rear side of the bottom plate 32a.
[0036] The light guide plate 50 formed in a plate member having a
rectangular plan view shape and is elongated in the long side
direction (X-axis direction) of the backlight chassis 32. The light
guide plate 50 is made from a resin (such as acrylic) highly
capable of light transmission (or with high transparency). As
illustrated in FIG. 3, the light guide plate 50 is arranged such
that a main plate surface (a light exit surface 50A) thereof faces
toward the liquid crystal panel 12 and one of side surfaces (a
light entrance surface 50D) faces a light emitting surface 22D of a
first light source 22 and a light emitting surface 26D of a second
light source 26. The light guide plate 50 is not limited to be
formed in a rectangular plan view shape and may be formed in any
other shapes.
[0037] As illustrated in FIG. 3, a plurality of light reflective
portions 51 are provided on a surface 50B (a rear surface 50B) of
the light guide plate 50 that is opposite from the light exit
surface 50A. The light reflective portions 51 are arranged in a
dotted pattern having a white color. The light reflective portions
51 are configured to reflect and scatter the light. Accordingly,
some of the rays of light that travel toward the light exit surface
50A after being reflected and scattered by the light reflective
portions 51 has an entrance angle that is not above the critical
angle (some of the rays of light are not totally reflected), and
thus the light can exit toward the liquid crystal panel 12 through
the light exit surface 50A. The light reflective portions 51 are,
for example, configured by arranging the dots in a zigzag pattern
(grid pattern, staggered pattern). The dots are formed by printing
metal oxide pastes on the rear surface 50B of the light guide plate
50, for example. Preferable examples of the printing method of the
dots include screen printing and ink-jet printing.
[0038] With the above configuration, the light exited from (each
light source set 21 of) the LED unit 20 enters the light guide
plate 50 through the light entrance surface 50D of the light guide
plate 50, and then is guided within the light guide plate 50 due to
the total reflection and is reflected and scattered by the light
reflective portion 51. Thus, the light exits from the light exit
surface 50A. Then, the light exiting from the light exit surface
50A is applied to the rear surface of the liquid crystal panel 12
after passing through the optical member 40. The light reflective
portions 51 are provided on an area corresponding to the opening
16a of the front chassis 16 (an area overlapping with the opening
16a in a plan view), for example.
[0039] As illustrated in FIG. 3, a light reflection sheet 30 is
arranged on the bottom plate 32a of the backlight chassis 32. The
light reflection sheet 30 is formed in a rectangular plan view
shape. The light reflection sheet 30 is arranged so as to cover
almost entire of the rear surface 50B of the light guide plate 50
and a rear surface of the LED unit 20. The light reflection sheet
30 is made of a synthetic resin, for example, and includes a front
surface having a white color that provides high light reflectivity.
The light exiting from the light guide plate 50 to the light
reflective sheet 30 is reflected again toward the light exit
surface 50A by the light reflective sheet 30. This improves light
use efficiency. The light reflection sheet 30 also has a function
of reflecting the light that is exited from the LED unit 20 to the
light reflection sheet 30 so as to enter the light entrance surface
50D of the light guide plate 50. The material and color, for
example, of the light reflection sheet 30 are not limited to those
of the present embodiment. Any light reflective sheets that can
reflect the light may be used.
[0040] As illustrated in FIG. 3, the optical member 40 is arranged
so as to cover the front surface of the light exit surface 50A of
the light guide plate 50. The optical member 40 includes a light
diffuser sheet 41, a prism sheet 42, and a reflection-type
polarizing sheet 43 arranged in this sequence from the light exit
surface 50A side. The light diffuser sheet 41 may be configured by
bonding a diffusion layer including light scattering particles
dispersed therein onto a front surface of a light transmissive
board made of synthetic resin. The light diffuser sheet 41 diffuses
the light that exits from the light exit surface 50A. The prism
sheet 42 controls the traveling direction of the light that passed
through the light diffuser sheet 41.
[0041] The reflection-type polarizing sheet 43 has a multilayer
structure in which layers having different reflective indexes are
alternately arranged, for example. The reflection-type polarizing
sheet 43 transmits p-wave of the light exiting through the light
exit surface 50A and reflects s-wave toward the light guide plate
50. The s-wave reflected by the reflection-type polarizing sheet 43
is reflected again toward the front side by the light reflection
sheet 30, for example. At this time, the reflected s-wave separates
into s-wave and p-wave. As described above, the reflection-type
polarizing sheet 43 allows the s-wave that is normally absorbed by
the polarizing plate of the liquid crystal panel 12 to be reused by
reflecting the s-wave toward the light guide plate side. This
improves light use efficiency (and thus brightness). An example of
the reflection-type polarizing sheet 43 is a product named "DBEF"
that is manufactured by Sumitomo 3M Limited.
[0042] As illustrated in FIG. 2, like the light guide plate 50,
each of the light diffuser sheet 41, the prism sheet 42, and the
reflection-type polarizing sheet 43 has a rectangular shape
extending along the X-axis direction in a plan view. The light
diffuser sheet 41, the prism sheet 42, and the reflection-type
polarizing sheet 43 have the same shape. The sheets 41 to 43 are
arranged so as to cover the front surface of the light exit surface
50A of the light guide plate 50. The shape of the sheets 41 to 43
included in the optical member 40 is not limited to the rectangular
shape in a plan view. The sheets 41 to 43 included in the optical
member 40 may be arranged so as to cover at least part of the front
surface of the light exit surface 50A of the light guide plate
50.
[0043] Next, the configuration of the LED unit 20 (the light source
unit) will be explained in detail. As illustrated in FIGS. 2 and 3,
the LED unit 20 is attached to an inner surface of one of the side
plates 32b with screws, for example. The side plates 32b extend in
the long-side direction (X-axis direction) of the backlight chassis
32. The LED unit 20 includes a plurality of light source sets 21
and an LED board 27 on which the light source sets 21 are arranged
as illustrated in FIG. 4. The LED board 27 is formed in a
rectangular shape extending in the X-axis direction. The light
source sets 21 are arranged in a line in the X-axis direction.
[0044] As illustrated in FIGS. 3 and 4, each light source set 21
includes a base 28, a first light source 22 and a second light
source 26. The first light source 22 and the second light source 26
are mounted on the base 28 formed in a rectangular plate shape
extending in the Z-axis direction. The first light source 22 and
the second light source 26 are provided in each light source set
21, and arranged in a direction (Z-axis direction) that is
perpendicular to an arrangement direction (X-axis direction) in
which the light source sets 21 are arranged on the LED board 27 (on
the X-Z plane). On the LED board 27 (X-Z plane), the first light
source 22 and the second light source 26 in each light source set
21 are not necessarily to be arranged in the direction
perpendicular to the arrangement direction of the light source sets
21 but may be arranged in a direction that crosses the arrangement
direction (the X-axis direction) of the light source sets 21.
[0045] In the present embodiment, the first light sources 22 that
are arranged close to an upper side in FIG. 4 and the first light
sources 22 that are arranged close to a lower side in FIG. 4 are
provided alternately in the X-axis direction. The second light
sources 26 that are arranged close to the upper side in FIG. 4 and
the second light sources 26 that are arranged close to the lower
side in FIG. 4 are provided alternately in the X-axis direction.
Accordingly, the first light sources 22 (or the second light
sources 26) of the light source sets 21 are arranged non-linearly
(in substantially a zigzag line).
[0046] Two adjacent light source sets 21 (21A and 21B) are arranged
such that the arrangement of the light sources 22, 26 of the light
source set 21 (21A) is inverted from the arrangement of the light
sources 22, 26 of the light source set 21 (21B). Specifically, the
first light source 22 (22A) in one of the light source sets 21
(21A) and the second light source 26 (26B) in the other one of the
light source sets 21 (21B) are arranged adjacent to each other in
the X-axis direction (in the arrangement direction in which the two
adjacent light source sets 21 are arranged). The second light
source 26 (26A) in one of the light source sets 21 (21A) and the
first light source 22 (22B) in the other one of the light source
sets 21 (21B) are arranged adjacent to each other in the X-axis
direction (in the arrangement direction of the two adjacent light
source sets 21). This arrangement configuration of the light
sources 22 and 26 may not be applied to all adjacent light source
sets 21 arranged on the LED board 27, and may be applied to at
least two adjacent light source sets 21 arranged thereon.
[0047] The first light source 22 is configured by sealing a first
LED chip 23 with a transparent resin material 24 (silicone resin),
for example. In other words, the first LED chip 23 is covered with
the resin material 24. The first LED chip 23 is configured to emit
at least a single color of light of red, green or blue. In the
present embodiment, a blue LED chip configured to emit blue light
is used. The blue LED chip has a main light emitting peak in a blue
wavelength range that is from 430 nm to 500 nm. The blue LED chip
can emit pure blue light.
[0048] Phosphors are contained in the resin material 24 in a
dispersed manner. The phosphors are excited by light from the first
LED chip 23 to emit light, the colors of which are different from
the color of the light emitted from the first LED chip 23. In the
present embodiment, for example, green phosphors and red phosphors
are contained in the resin material 24 at a certain rate in a
dispersed manner. The green phosphors are excited by blue light
emitted from the first LED chip 23 to emit green light. The red
phosphors are excited by blue light emitted from the first LED chip
23 to emit red light.
[0049] Blue light (light including a blue component) is emitted
from the first LED chip 23. Green light (light including a green
component) is emitted from green phosphors. Red light (light
including a red component) is emitted from red phosphors.
Accordingly, the first light source 22 emits substantially white
light (including white light and substantially white light with a
blue tinge). In addition, yellow light is obtained by mixture of
light having a green component from green phosphors and light
having a red component from red phosphors, and accordingly, the
phosphors contained in the resin material 24 are excited by light
from the first LED chip 23 to emit light having a yellow component.
Instead of the configuration provided with the green phosphors and
the red phosphors, phosphors (for example, YAG phosphors) that emit
yellow light by excitation by blue light may be provided.
[0050] Chromaticity of the first light source 22 varies depending
on the absolute or relative amount of green phosphors and red
phosphors contained in the resin material 24. The amount of green
phosphors and red phosphors can be controlled as appropriate, and
therefore the chromaticity of the first light source 22 (and thus
the light source set 21) can be controlled. In the present
embodiment, the green phosphor has a main light emitting peak in a
green wavelength range that is from 500 nm to 570 nm, for example.
The red phosphor has a main light emitting peak in a red wavelength
range that is from 610 nm to 780 nm, for example.
[0051] The green phosphor and the red phosphor will be further
explained in detail. For example, a .beta.-SiAlON phosphor of a
SiAlON-based phosphor, which is a nitride, is preferably used as a
green phosphor. The .beta.-SiAlON phosphor emits green light with
high efficiency compared to sulfide phosphors and oxide phosphors
and the emitted green light contains especially highly chromatic
purity of a green color. Therefore, the .beta.-SiAlON phosphor is
very useful for controlling the chromaticity of the first light
source 22. Specifically, Eu (europium) is used as an activator for
the .beta.-SiAlON phosphor. The general formula thereof is
expressed as Si6-zAlzOzN8-z:Eu (z shows the amount of solid
solution) or (Si,Al)6(O,N)8:Eu.
[0052] The green phosphor may be another phosphor other than the
above .beta.-SiAlON phosphor and altered if necessary.
(Y,Gd)3Al5O12:Ce of a YAG-based phosphor is preferable to be used
as the green phosphor because light emission with high efficiency
is achieved. Examples of the green phosphor include the following
inorganic phosphors: (Ba,Mg)Al10O17:Eu,Mn; SrAl2O4:Eu;
Ba1.5Sr0.5SiO4:Eu; BaMgAl10O17:Eu,Mn; Ca3(Sc,Mg)2Si3O12:Ce;
Lu3A15O12:Ce; CaSc2O4:Ce; ZnS:Cu,Al; (Zn,Cd)S:Cu,Al; Y3Al5O12:Tb;
Y3(Al,Ga)5O12:Tb; Y2SiO5:Tb; Zn2SiO4:Mn; (Zn,Cd)S:Cu; ZnS:Cu;
Gd2O2S:Tb; (Zn,Cd)S:Ag; Y2O2S:Tb; (Zn,Mn)2SiO4; BaAl12O19:Mn;
(Ba,Sr,Mg)O.aAl2O3:Mn; LaPO4:Ce,Tb; Zn2SiO4:Mn; CeMgAl11O19:Tb; and
BaMgAl10O17:Eu,Mn.
[0053] For example, a CaAlSiN.sub.3-based phosphor, commonly known
as a CASN phosphor in the CASN system, which is a nitride, is
preferably used as a red phosphor. The CASN phosphor is allowed to
emit red light with high efficiency compared to sulfide phosphors
and oxide phosphors. Specifically, Eu (europium) is used as an
activator for the CASN phosphor, which is expressed as CaAlSiN3:Eu.
The red phosphor may be another phosphor other than the above CASN
phosphor and altered if necessary. Moreover, examples of the red
phosphors include the following inorganic phosphors:
(Sr,Ca)AlSiN3:Eu; Y2O2S:Eu; Y2O3:Eu; Zn3(PO4)2:Mn; (Y,Gd,Eu)BO3;
(Y,Gd,Eu)2O3; YVO4:Eu; and La2O2S:Eu,Sm.
[0054] The second light source 26 is configured to emit at least a
single color of light of cyan, yellow or magenta. In the present
embodiment, an LED configured to emit yellow light is used, for
example. The "LED" here may include at least an LED chip therein.
The following configurations are applicable to the second light
source 26: an LED chip configured to emit yellow (cyan or magenta)
light; LED chips in combination configured to emit yellow (cyan or
magenta) light; and an LED chip and phosphors configured to emit
yellow (cyan or magenta) light.
[0055] The first light sources 22 and the second light sources 26
are arranged such that light axes thereof extend in a direction
parallel to a display surface of the liquid crystal panel 12 or a
light exit surface 50A of the light guide plate (Y-axis direction).
As illustrated in FIG. 3, a light emitting surface 22D of the first
light source 22 and a light emitting surface 26D of the second
light source 26 face a side surface (light entrance surface 50D) of
the light guide plate 50.
[0056] The LED board 27 is made of synthetic resin. A front surface
(a surface facing the light guide plate 50) of the LED board 27
have a white color that provides high light reflectivity. With such
a configuration, light reflects off the front surface of the LED
board 27 to the light guide plate. Therefore, light use efficiency
is improved.
[0057] As illustrated in FIG. 2, the LED board 27 has a rectangular
plate shape extending in the X-axis direction. The long side of the
LED board 24 is slightly shorter than (or substantially the same
as) that of the bottom plate 32a. Further, mounting holes (not
illustrated) that are through holes are formed in the bottom plate
32a to fix the LED board 24 with screws.
[0058] A wiring pattern (not illustrated) made of metal film is
provided on the LED board 27 and the first light sources 22 (the
first LED chip 23) and the second light sources 26 are electrically
connected to the wiring pattern. A control board, which is not
illustrated, is connected to the LED board 27. The control board
supplies the power required to turn on the first light sources 22
and the second light sources 26 and controls the drive of the first
light sources 22 and the second light sources 26.
[0059] Next, effects in the present embodiment will be explained.
The LED unit 20 of the present embodiment includes the light source
sets 21 and the LED board 27 on which the light source sets 21 are
arranged. Each of the light source sets 21 includes the first light
source 22 and the second light source 26. The first light source 22
includes the first LED chip 23 and phosphors. The first LED chip 23
is configured to emit at least a single color of light of red,
green or blue. The phosphors are excited by light from the first
LED chip 23 to emit light, colors of which are different from the
color of the light emitted from the first LED chip 23. The second
light source 26 is configured to emit at least a single color of
light of cyan, magenta or yellow. The two adjacent light source
sets 21A and 21B are arranged such that the first light source 22A
of the light source set 21A and the second light source 26B of the
light source set 21B are arranged adjacent to each other in the
X-axis direction (in the arrangement direction in which the two
adjacent light source sets 21A and 21B are arranged).
[0060] In the LED unit 20 of the present embodiment, each of the
light source sets 21 includes the first light source 22 and the
second light source 26. With such a configuration, the color
reproduction range is widened compared to a configuration in which
only the first light sources 22 are provided. In such a
configuration of the LED unit including a plurality of light source
sets 21 each of which has the first light source 22 and the second
light source 26, if the two adjacent light source sets (21A, 21B)
are arranged such that the first light source 22A of the light
source set 21A is arranged adjacent to the first light source 22B
of the light source set 21B in the arrangement direction (in the
X-axis direction) of the two adjacent light source sets 21A and
21B, the first light sources 22A and 22B (or the second light
sources 26A and 26B) are locally arranged on the LED board 27. This
may cause uneven brightness or color unevenness.
[0061] For example, the first light sources 22 (22A and 22B) are
arranged on one side of the LED unit 20 (on an upper side of FIG.
4) and the second light sources 26 (26A and 26B) are arranged on
another side thereof (on a lower side of FIG. 4). With such a
configuration, light from the first light sources 22 mainly exits
from the one side of the LED unit 20, and light from the second
light sources 26 mainly exits from the another side thereof.
Accordingly, different types of light exits from the one side of
the LED unit 20 and from the another side thereof, and thus uneven
brightness or color unevenness is likely to occur.
[0062] In the present embodiment, the two adjacent light source
sets 21A and 21B are arranged such that the first light source 22A
of the light source set 21A and the second light source 26B of the
light source set 21B are arranged adjacent to each other in the
arrangement direction of the two adjacent light source sets 21A and
21B. With such a configuration, the first light sources 22 (or the
second light sources 26) are less likely to be arranged locally on
the LED board 27, thereby reducing uneven brightness and color
unevenness in the light exiting from the LED unit 20.
[0063] In the LED unit 20, the first light source 22 and the second
light source 26 of each light source set 21 are arranged on the LED
board 27 in a direction (the Z-axis direction in the present
embodiment) that crosses the arrangement direction of the light
source sets 21.
[0064] The first light source 22 is configured by sealing the first
LED chip 23 with the resin material 24. The phosphors are contained
in the resin material 24 in a dispersed manner. The phosphor
content is appropriately controlled, and thus the ratio between
light from the first light source 22 and light emitted by the
phosphors excited therefrom varies. Therefore, the chromaticity of
light from the first light source 22 is controlled.
[0065] The first LED chip 23 is a blue LED chip configured to emit
blue light. The phosphors include a red phosphor and a green
phosphor. The red phosphor is excited by light from the first LED
chip 23 to emit red light. The green phosphor is excited by light
from the first LED chip 23 to emit green light. With such a
configuration, substantially white light (including white light and
substantially white light with a blue tinge) can be emitted from
the first light source 22. Moreover, the chromaticity of light from
the second light source 26 is controlled, and thus the chromaticity
of light exited from the light source set 21 is controlled.
[0066] If the first light source 22 emits white light with a blue
tinge, an LED configured to emit yellow light that is a
complementary color of blue is used for the second light source 26.
This allows the light source set 21 to emit light that is closer to
white light. Moreover, if the first light source 22 emits white
light with a green tinge, an LED configured to emit magenta light
that is a complementary color of green is used for the second light
source 26. This allows the light source set 21 to emit light that
is closer to white light. The color combination of light of the
first light source 22 and the second light source 26 may be altered
if necessary.
[0067] The red phosphor is a CASN phosphor. A CASN phosphor that is
a nitride phosphor is used as a red phosphor. The CASN phosphor is
allowed to emit red light with high efficiency compared to sulfide
phosphors and oxide phosphors.
[0068] The green phosphor is a SiAlON-based phosphor. A
SiAlON-based phosphor that is a nitride is used as a green
phosphor. The SiAlON-based phosphor is allowed to emit green light
with high efficiency compared to sulfide phosphors and oxide
phosphors. In addition, light emitted from the SiAlON-based
phosphor has color purity higher than a YAG phosphor, for example.
Therefore, the chromaticity can be controlled easily.
[0069] The green phosphor may be a YAG-based phosphor.
[0070] Next, the backlight unit 34 of the present embodiment
includes the LED unit 20 and the housing member 15 that houses the
LED unit 20.
[0071] The backlight unit 34 includes the light guide plate 50 that
includes the light entrance surface 50D and the light exit surface
50A. The light entrance surface 50D faces the light emitting
surface 22D of the first light source 22 and the light emitting
surface 26D of the second light source 26. Light from the light
emitting surfaces 22D and 26D enters the light guide plate 50
through the light entrance surface 50D and exits from the light
guide plate 50 through the light exit surface 50A.
[0072] In the present embodiment, the LED unit 20 in which wide
color reproduction range is achieved is provided. Furthermore, the
backlight unit 34, the liquid crystal display 10 and the television
receiver TV including the LED unit 20 are provided.
Second Embodiment
[0073] A second embodiment according to the present invention will
be explained with reference to FIGS. 5 to 7. In the second
embodiment, a liquid crystal display device 110 includes components
different from the first embodiment. The construction, operations
and effects as same as the first embodiment will not be
explained.
[0074] FIG. 5 illustrates an exploded perspective view of the
liquid crystal display device 110 according to the present
embodiment. An upper side in FIGS. 5 and 6 corresponds to a
front-surface side and a lower side in FIGS. 5 and 6 corresponds to
a rear-surface side. An entire shape of the liquid crystal display
device 110 is a landscape rectangular. As illustrated in FIG. 5,
the liquid crystal display device 110 includes a liquid crystal
panel 116 as a display panel, and a backlight unit 124 as an
external light source. The liquid crystal panel 116 and the
backlight unit 124 are integrally held by a top bezel 112a, a
bottom bezel 112b, side bezels 112c (hereinafter a bezel set 112a
to 112c) and the like. The construction of the liquid crystal panel
116 that is as same as the first embodiment will not be
explained.
[0075] In the following, the backlight unit 124 will be explained.
The backlight unit 124 is a so-called edge-light-type
(side-light-type) backlight unit like the first embodiment.
However, the configuration is different from the first embodiment
in that the LED units 150 are arranged on both side end portions of
the light guide plate 120. As illustrated in FIG. 5, the backlight
unit 124 includes a backlight chassis 122, optical members 118, a
top frame 114a, a bottom frame 114b, side frames 114c and a light
guide plate reflection sheet 134a. In the following, the top frame
114a, the bottom frame 114b, and the side frames 114c are referred
to as a frame set 114a to 114c.
[0076] The liquid crystal panel 116 is sandwiched between the bezel
set 112a to 112c and the frame set 114a to 114c. A reference
numeral 113 represents an insulating layer configured to insulate a
driving circuit board 115 (see FIG. 6) for driving the liquid
crystal panel 116. The substantially box-shaped backlight chassis
122 has an opening on the front-surface side (on the light exit
side and the liquid crystal panel 116 side).
[0077] The optical members 118 are provided on the front-surface
side of the light guide plate 120. The optical members 118 include
laminated layers of light diffuser sheets, prism sheets and
reflecting type polarizing sheets as appropriate. The light guide
plate reflection sheet 134a is provided on the rear-surface side of
the light guide plate 120. Furthermore, the backlight chassis 122
houses a pair of cable holders 131, a pair of mounting members 119,
a pair of LED units 150 and the light guide plate 120 in the
backlight chassis 122. The LED units 150, the light guide plate 120
and the light guide plate reflection sheet 134a are supported each
other by a rubber bushing 133. A power supply circuit board (not
illustrated) supplying power to the LED units 150 and a protection
cover 123 for protecting the power supply circuit board are mounted
on the rear side of the backlight chassis 122. The pair of cable
holders 131 is arranged in the short-side direction of the
backlight chassis 122 and holds cables electrically connected
between the LED units 150 and the power supply circuit board.
[0078] FIG. 6 illustrates a vertical sectional view of the
backlight unit 124. As illustrated in FIG. 6, the backlight chassis
122 includes a bottom plate 122a having the bottom surface 122z
thereon and side plates 122b and 122c, each of which rises
shallowly from an outer edge of the corresponding side of the
bottom plate 122a. The backlight chassis 122 supports at least the
LED unit 150 and the light guide plate 120.
[0079] Furthermore, each of the mounting members 119 includes a
bottom surface portion 119a and a side surface portion 119b that
rises from one of outer edges of the long side of the bottom
surface portion 119a. Each of the mounting members 119 is formed in
an L-shape and provided in the direction along one of long sides of
the backlight chassis 122. The bottom surface portions 119a of the
mounting members 119 are fixed to the bottom plate 122a of the
backlight chassis 122. The LED units 150 (an LED board 157) extend
in the direction along respective long sides of the backlight
chassis 122. The LED units 150 are fixed to the side surface
portions 119b of the mounting members 119 such that the light exit
sides of the LED units 150 face each other. Accordingly, the bottom
plate 122a of the backlight chassis 122 supports the LED units 150
through the mounting members 119. The mounting members 119
dissipate heat generated in the LED units 150 outside the backlight
unit 124 through the bottom plate 122a of the backlight chassis
122.
[0080] As illustrated in FIG. 5, the light guide plate 120 is
provided between the pair of LED units 150. The frame set 114a to
114c and the backlight chassis 122 sandwich the LED units 150, the
light guide plate 120 and the optical members 118. Furthermore, the
frame set 114a to 114c and the backlight chassis 122 fix the light
guide plate 120 and the optical members 118. The configuration of
the light guide plate 120 that is same as that of the light guide
plate 50 in first embodiment will not be explained.
[0081] As illustrated in FIG. 6, the driving circuit board 115 is
provided on the front-surface side of the bottom frame 114b. The
driving circuit board 115 is electrically connected to the display
panel 116 to supply image data and various control signals that are
necessary to display images with the display panel 116. Front
reflection sheets 134b are provided on surfaces of the top frame
114a and the bottom frame 114b that face the LED units 150. The
front reflection sheets 134b extend in the long-side direction of
the light guide plate 120. Rear reflection sheets 134c are provided
on a part of the bottom plate 122a of the backlight chassis 122
that faces the LED units 150. An edge part of the rear reflection
sheet 134c is arranged closely to the light guide plate 120 and
provided so as to overlap an edge part of the light guide plate
reflection sheet 134a in a plan view.
[0082] In the present embodiment, the LED unit 150 has a
configuration different from that in the first embodiment. FIG. 7
illustrates a magnified view of a vicinity of the LED unit 150 in
FIG. 6. As illustrated in FIG. 7, a light source set 151 in the LED
unit 150 includes the first light source 22, the second light
source 26 and a housing 154 that houses the first light source 22
and the second light source 26 therein. In the present embodiment,
the first light source 22 and the second light source 26 are
directly mounted on the LED board 157 without having the base 28 of
the first embodiment.
[0083] A diffuser lens 159 is mounted on each of the light source
sets 151. The diffuser lens 159 is provided so as to cover the
light emitting surface 22D of the first light source 22 and the
light emitting surface 26D of the second light source 26. The
diffuser lens 159 is formed in a hemispherical shape, for example.
A curved surface of the diffuser lens 159 faces the light entrance
surface 50D of the light guide plate 50. With such a configuration,
the diffuser lens 159 is configured to diffuse light exiting
through the light emitting surfaces 22D and 26D.
[0084] In the present embodiment, the diffuser lens 159 diffuses
light from the first light source 22 and the second light source
26, and accordingly, an illumination area illuminated with light
exiting from each light source set 151 is increased. This causes
the arrangement intervals between the light source sets 151 to be
increased (namely, the total number of light source sets 151 is
reduced) and achieves uniform brightness.
Third Embodiment
[0085] An LED unit 220 according to a third embodiment of the
present invention will be explained with reference to FIG. 8. In
the LED unit 220 of the present embodiment, an arrangement
direction of the light source sets 21 is different from that of the
first embodiment. In the present embodiment, the first light source
22 and the second light source 26 in each of the light source sets
21 are arranged in the same direction (X-axis direction) as the
arrangement direction of the light source sets 21 on an LED board
227. With such an arrangement of the light source sets 21, a width
of the LED board 227 (a length of the LED board 227 in the Z-axis
direction) can be smaller than the widths of the LED boards 27 and
157.
[0086] In the present embodiment, in the two adjacent light source
sets 21 (for example, 21C and 21D), the first light source 22 (22D)
in one of the light source sets 21 (21D) and the second light
source 26 (26C) in the other one of the light source sets 21 (21C)
are arranged adjacent to each other in the X-axis direction (the
arrangement direction of the two adjacent light source sets 21). In
other words, the first light source 22 and the second light source
26 are alternately arranged in the X-axis direction in the two
adjacent light source sets 21C and 21D. With such a configuration,
the first light sources 22 (or the second light sources 26) are
less likely to be arranged locally on the LED board 227, compared
to a configuration where the first light sources 22 (or the second
light sources 26) are arranged adjacent to each other. This results
in reducing uneven brightness and color unevenness in light exiting
from the LED unit 220.
Other Embodiments
[0087] The present invention is not limited to the above
embodiments described in the above description and the drawings.
The following embodiments are also included in the technical scope
of the present invention, for example.
[0088] (1) In the above embodiments, the first light source
includes a blue LED chip and phosphors configured to emit light in
red and green colors. However, the LED chip of the first light
source may be configured to emit at least a single color of light
of red, green or blue. Namely, the LED chip of the first light
source may be configured to emit two or more colors (or mixture of
two or more colors) of light among red, green and blue. The
phosphors of the first light source may be configured to emit
colors of light that are different from colors of light emitted by
the first LED chip. The second light source may be an LED that is
configured to emit at least a single color of light of cyan,
magenta or yellow. Namely, the second light source may be an LED
that is configured to emit two or more colors (or mixture of two or
more colors) of light among cyan, magenta and yellow.
[0089] (2) In the second embodiment, the single diffuser lens 159
covers the light emitting surface 22D of the first light source 22
and the light emitting surface 26D of the second light source 26.
However, each of the light emitting surface 22D of the first light
source 22 and the light emitting surface 26D of the second light
source 26 may be covered with an independent diffuser lens.
[0090] (3) The arrangement direction of the first light source and
the second light source in a single light source set is not limited
to the direction illustrated in the above embodiments (the X-axis
direction or the Z-axis direction) but may be altered if
necessary.
[0091] (4) The shape of the diffuser lens 159 is not limited to a
hemispherical shape. The diffuser lens 159 may be formed in any
shape as long as the diffuser lens 159 may diffuse light from the
first light source or the second light source. For example, the
diffuser lens 159 may be a cylindrical lens configured to diffuse
light in a single direction.
[0092] (5) The configuration of the optical member 40 is not
limited to the above embodiments. Types of the sheets and the
number of each type of the sheets included in the optical member 40
may be altered if necessary.
[0093] (6) In the above embodiments, TFTs are used as switching
components of the liquid crystal display device. However, the
technology described above can be applied to liquid crystal display
devices including switching components other than TFTs (e.g., thin
film diode (TFD)). Moreover, the technology can be applied to not
only color liquid crystal display devices but also black-and-white
liquid crystal display devices.
[0094] (7) In the above embodiments, the liquid crystal display
device including the liquid crystal panel as a display panel. The
technology can be applied to display devices including other types
of display components.
[0095] (8) In the above embodiments, the television receiver
including the tuner is used. However, the technology can be applied
to a display device without a tuner.
EXPLANATION OF SYMBOLS
[0096] 10, 110: liquid crystal display device (display device), 12,
116: liquid crystal panel (display panel), 15: housing member, 20,
150, 220: LED unit (light source unit), 21, 151: light source set,
21A, 21B: two adjacent light source sets, 22: first light source,
22A: first light source (first light source in one of the light
source sets), 22D: light emitting surface of the first light
source, 23: first LED chip, 24:resin material, 26: second light
source, 26B: second light source (second light source in another
one of the light source sets), 22D: light emitting surface of the
second light source, 27, 157, 227: LED board (board), 34, 124:
backlight unit (lighting device), 50, 120: light guide plate, 50A:
light exit surface, 50D: Light entrance surface, 159: diffuser
lens, TV: television receiver
* * * * *